From a3af9c389a7f3e675313f442fdd8c247c1cdb66b Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Tue, 16 Jun 2009 15:32:10 -0700 Subject: [PATCH] page allocator: do not check for compound pages during the page allocator sanity checks A number of sanity checks are made on each page allocation and free including that the page count is zero. page_count() checks for compound pages and checks the count of the head page if true. However, in these paths, we do not care if the page is compound or not as the count of each tail page should also be zero. This patch makes two changes to the use of page_count() in the free path. It converts one check of page_count() to a VM_BUG_ON() as the count should have been unconditionally checked earlier in the free path. It also avoids checking for compound pages. [mel@csn.ul.ie: Wrote changelog] Signed-off-by: Mel Gorman Signed-off-by: Nick Piggin Reviewed-by: Christoph Lameter Cc: KOSAKI Motohiro Cc: Pekka Enberg Cc: Peter Zijlstra Cc: Dave Hansen Cc: Lee Schermerhorn Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/page_alloc.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index fd8e3ca0cf3b..8485735fc690 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -421,7 +421,7 @@ static inline int page_is_buddy(struct page *page, struct page *buddy, return 0; if (PageBuddy(buddy) && page_order(buddy) == order) { - BUG_ON(page_count(buddy) != 0); + VM_BUG_ON(page_count(buddy) != 0); return 1; } return 0; @@ -497,7 +497,7 @@ static inline int free_pages_check(struct page *page) { if (unlikely(page_mapcount(page) | (page->mapping != NULL) | - (page_count(page) != 0) | + (atomic_read(&page->_count) != 0) | (page->flags & PAGE_FLAGS_CHECK_AT_FREE))) { bad_page(page); return 1; @@ -642,7 +642,7 @@ static int prep_new_page(struct page *page, int order, gfp_t gfp_flags) { if (unlikely(page_mapcount(page) | (page->mapping != NULL) | - (page_count(page) != 0) | + (atomic_read(&page->_count) != 0) | (page->flags & PAGE_FLAGS_CHECK_AT_PREP))) { bad_page(page); return 1; -- 2.39.2